1. Field of the Invention
The present invention relates to an improvement of a multiplex writing implement having a plurality of ball-point pen elements.
2. Description of the Prior Art
In general, there are known multiplex writing implements of rotary, clicking and slider types and the like, which have a plurality of writing elements such as a mechanical pencil, ball-point pen and the like, and selectively allow one of the writing tips to move in and out through the front end thereof.
Meanwhile, conventionally known oil based ball-point pens use an ink having a high viscosity of some thousands of mPa.multidot.S or more, hence a considerably large resistance arises when the ball rolls and the ink flows out from the writing point, producing an uncomfortable writing sensation. Further, the pen of this type suffers from problems in that a lesser amount of ink can flow from the writing point during writing and in that blobbing, hence lines drawn can be irregular in parts, the density of the written trace is light and a strong pressure for writing is needed.
As an improvement of the oil based ball-point pen, there has been recently developed a ball-point pen for water based ink which uses an ink having an intermediate viscosity between viscosity of the above water based type and that of the oil based type (ranging from a few mPa.multidot.S to some thousands of mPa.multidot.S) and hence is called a medium viscosity ink. This ball-point pen uses water based ink having a relatively low viscosity which has so-called thixotropy, that is, a characteristic which lowers the viscosity of ink as the tip ball rolls, so that the ink can smoothly flow out.
As an improvement of oil based ball-point pens, it is possible to consider a ball-point pen which uses an oil based ink having both a low viscosity and an excellent drought resistance.
Because of the less viscosity of ink, any of the above ball-point pens using medium viscosity water based ink or low viscosity oil based ink markedly suffers from the forward leakage problem of ink oozing out from a gap, if any, between the ball point and the tip holder when it is held with its pen tip down, and also suffers from the problem of ink leaking backward when the pen is used with its tip upward or when it receives impacts and the like. When backward or forward leakage of ink occurs, there is a risk of the ink staining clothes and the like. Further, if, while the tip ball and the ball-holder in the point assembly remain in contact with the tapering inner surface of the mouthpiece, the writing tips are made to move in and out repeatedly through the front end opening of the mouthpiece, the inner surface of the mouthpiece is stained with ink, degrading its appearance.
Liquid applicators using a white pigment for correcting character errors etc., are known.
Because the white pigment readily separates from its solvent, applicators of this kind are formed of a flexible container with the ink, a ball, etc. confined therein and the ink and solvent need to be mixed by shaking when it is used. Also the container needs to be pressed on its side part to eject the ink. However, when a reduced amount of ink remains, ink will not be ejected even with strong pressure acting on the side wall of the container, causing user irritation. Further, in order to avoid the applicator's tip drying, the tip is adapted to be sealed with a cap.